Modern ocular surgical systems, and in particular, modern ophthalmic and vitro-retinal surgical systems, for example, are designed to monitor and display multiple parameters of a surgical device or instrument that is connected to the surgical system and controlled by the surgeon through the use of a foot pedal. Such systems can be complex given the multiple parameters that must be displayed and controlled by a surgeon, particularly during a surgical procedure.
Certain known ocular surgical systems allow for application of ultrasound energy at a fixed level. For example, in a phacoemulsification surgical system, the foot pedal acts as an on/off switch to activate and deactivate ultrasound energy that is at a particular power level. When the foot pedal is pressed, the device is activated and the power level is constant and without interruptions, that is “continuous.” Continuous power is approximately proportional to the amount of voltage applied to the piezoelectric crystals in the handpiece.
“Continuous” power systems were improved by the introduction of “linear” mode, which allows a surgeon to control power in a variable manner. A surgeon controls power based on the foot pedal position so that the power is proportional to or linear with respect to the displacement of the foot pedal. Thus, more power is provided as the surgeon presses the foot pedal, and less power is provided as the foot pedal is released. Further improvements involved the introduction of “pulse” mode. In “pulse” mode, energy is provided in periodic pulses at a constant duty cycle. The surgeon increases or decreases the amount of power by pressing or releasing the foot pedal, which increases or decreases the amplitude of the fixed-width pulses. Further enhancements involved the introduction of “burst” mode. In “burst” mode, power is provided through a series of periodic, fixed width, constant amplitude pulses. Each pulse is followed by an “off” time. The off-time is varied by the surgeon by pressing and releasing the foot pedal.
In order to accommodate continuous, “linear,” “pulse” and “burst” mode and their operating parameters, known user interfaces of ocular surgical systems typically include several human actionable controllers and fields or elements that occupy particular positions on a display screen. Some known user interfaces include buttons, arrows, switches, bars and/or knobs for setting desired numeric values of operating characteristics of the surgical system. Certain parameters are fixed or have a constant value regardless of the foot pedal position, whereas other parameters vary, e.g., vary linearly, with the foot pedal. The interface is manipulated by a surgeon to provide control signals to the surgical instruments which, in turn, control the modes or types of pulses that are generated.
FIGS. 1 and 2 illustrate one known interface for a phacoemulsification surgical system. A surgeon manually selects the power mode from a selection bar or menu 10. In this interface, the menu 10 includes “Ultrasound Continuous,” “Ultrasound Pulse,” and “Ultrasound Burst” menu bars 12, 14 and 16, respectively. In the example illustrated in FIGS. 1 and 2, the continuous power menu bar 12 is selected from the menu 10. The power limit is represented in a field 20. The maximum amount of continuous power or the power limit is adjusted using up/down arrows 24. In this example, the continuous power limit is selected to be “35” or 35% of the maximum allowed power. The continuous power varies linearly, as shown by the line 26 in the background of the power limit field 20 up to a maximum value of 35%. The current power level is provided in a field 28. In the illustrated example, the current power is “0” or 0% in this example since the screen represents current power when the foot pedal is released. Pressing the foot pedal results in power increasing linearly from 0% to 35%. When the surgeon wants to change from “continuous” mode to another mode, the surgeon selects the “ultrasound continuous” bar 12 so that the menu 10 of available pulse modes is displayed. The surgeon can then select another mode from the menu 10.
Application of periodic ultrasound pulses can be described based on power, the duration of the pulses, the “On” or active time, and the duration of “Off” time or the duration between pulses. Alternatively, pulses can be specified using pulse rate and duty cycle. Pulse rate is the number of pulses contained in unit time. Duty cycle is the portion of the ultrasound cycle when the ultrasound is active. In other words, duty cycle is the ratio of On/(On+Off).
FIG. 3 illustrates “Ultrasound Pulse” menu bar 14 being selected from the menu 10. A surgeon manually selects a maximum power level of 35%, which varies linearly as the foot pedal is pressed and released. In addition, the interface includes a field 30 for the pulse rate or pulses per second (pps) and a field 40 for the “on-time” (% Time on). The number of pulses per second (pps) and the on-time, however, do not vary with movement of the foot pedal. Rather, the pps is fixed at 14 pps using arrows 34, and the on-time is fixed at 45% using arrows 44. Thus, the pps and on-time values do not change when the foot pedal is displaced and must be manually adjusted by the surgeon using arrows 34 and 44. Power increases linearly from 0-35% as the foot pedal is pressed, and is delivered at a fixed rate of 14 pulses per second at a fixed 45% duty cycle.
Referring to FIGS. 2 and 4, when “Ultrasound Burst” mode is selected from the menu 10, the same limit and power field 28 and limit field 20 are provided. The power varies linearly with the foot pedal, as discussed above. Rather than pps and on time fields 30 and 40 (as shown in FIG. 3), the interface displays a field 50 for on-time or On (ms) and a field 60 for off time or Off (ms) when in “burst” mode. The On (ms) value is fixed and does not change when the foot pedal is moved. The on-time (ms) is shown fixed at 70 ms and can be adjusted using arrows 54. The Off time decreases from a value to 0 ms with the foot pedal displacement. In this “burst” mode, the power increases from 0-40% as the foot pedal is depressed by changing the “off-time”, and the duration of each pulse remains a constant 70 ms throughout displacement of the foot pedal.
While known interfaces have been successfully used to perform phacoemulsification and vitreo-retinal surgical procedures in the past, they can be improved. Particularly, the visual and functional aspects of interfaces can be enhanced so that surgeons can select and control different surgical characteristics and pulse modes depending on the particular procedure being performed and surgical conditions encountered. User interfaces should include additional controllable display elements that allow different modes and surgical parameters to be quickly and easily adjusted. These improvements should be made without unduly complicating the user interface and how it functions. Further, interfaces should be capable of effectively representing various operating parameters of various ultrasound driving modes, including continuous, linear, pulse, burst, and new modes, which can be combinations and modifications of known modes. Being able to quickly adjust pulse parameters in an understandable manner also simplifies setting up the equipment, reduces operating costs and improves safety.